On 07/15/2015 02:23 PM, Owen DeLong wrote:
I will point out that nobody has said “what the F*** were they thinking” when they made it possible to use 4GB of RAM instead of just 640k, but lots of people have said “what the F*** were they thinking when they limited it to 640k.”
That 640k was the architectural limit imposed on Intel 16-bit 8086 system implementations, once you allocated fixed space for ROM. This was specific to the "IBM PC". This has to do with the 20-bit addressing used in the 8086. One could "grow" the address space externally, and some computer systems (not "IBM PC compatible") did so. Again, the 4-GB RAM limits is an architectural limit of the hardware; there is no "speed-of-light" limit in the amount of DRAM one can have in a system. Let's review the bidding on Internet Protocol, shall we? APRANET NCP (1970) -- 8-bit host Version 0 -- can't figure out the limit, if any; 4-bit "chunks" Version 1 -- 16-bit net/host address Version 2 -- variable! in octet increments Version 3 -- (not available) Version 4-78jun -- variable! in octet increments Version 4-78sep -- 32 bit net/host address, Class A (8-bit net) Version 5 -- (experimental circuit-switch protocol) Version 6 -- 128-bit